In general, a projection-type display or video projector displays an image that corresponds to a video signal upon a projection screen or other surface (e.g., wall). One of the major characteristics of projection-type display devices is their ability to display images that are larger in size than images produced by other displays such as CRT (cathode-ray tube) or LCD (liquid crystal display). Projection-type display devices have relatively smaller size compared to the image capable of being projected.
Traditionally, these video projection devices are widely used for business presentations, classroom training, home theater, etc. For example, projection devices are widely used in many schools and institutions to project onto an interactive white board during the course of teaching students.
Most modern projection devices are capable of correcting distortion, focus, and other inconsistencies by way of manual controls. However, to date, conventional projection-type display devices have been designed in a fixed CRT/LCD traditional mindset, such as single video output per device, or a lack of portability for a large image.